Observational study of the PM2.5 and O3 superposition-composite pollution event during spring 2020 in Beijing associated with the water vapor conveyor belt in the northern hemisphere. (1st March 2022)

• Record Type: Journal Article
• Authors: Wang, Jizhi; Yang, Yuanqin; Jiang, Xiaofei; Wang, Deying; Zhong, Junting; Wang, Yaqiang
• Is Part Of: Atmospheric environment. Volume 272(2022)
• Publication Date: 2022-03-01
• Subjects: Superposition-composite influence -- O3 and PM2.5 -- Super-saturation -- Condensation -- Water vapor conveyor belt -- Power exponential law; Air -- Pollution -- Periodicals; Air -- Pollution -- Meteorological aspects -- Periodicals; 551.51
• DOI: 10.1016/j.atmosenv.2022.118966
• Languages: English
• ISSNs: 1352-2310

Abstract

Abstract: Unlike the heavy haze situations in previous years, the emergence of a water vapor conveyor belt flowing through North China is an important factor in the foggy-haze event during the 48-h snowfall in Beijing and its surroundings, which disrupted the customary pollution snow removal atmospheric purification. ①In the spring of 2020, during a period of negative emissions increment and weak human activity impact, a special interaction between the high humidity content of large-scale continuous water vapor transmission and the weather-scale daily cycling radiation cycle change (due to daily change of sun's zenith angle), as well as the atmospheric microphysical process, provided rare meteorological conditions for the superposition-compound growth of PM2.5 and O3 pollution. The water vapor conveyor belt, through enhanced transmission of easterly wind momentum, induced a high value super-saturation signal ( S ) and condensation rate ( f c ), resulting in 48 consecutive hours of snow in Beijing, but was also conducive to fine particulates, including precursor emissions, through a microphysical humidification process, which became synchronized. ②The weather-scale process impact refers to the cloud height rise in the daytime and decrease at night. Due to the daily fluctuations in cloud height, the concentration of O3 followed a coordinated daily cycle. During the day, when the sun's zenith angle going on the top, the PM2.5 and O3 superposition composite effects occur. Therefore, even during a negative emission period, PM2.5 and O3 superposition-composite serious pollution events occur as usual, rather than the expected possible atmospheric cleaning through snow. Highlights: Special meteorological condition is resulting in composite pollution of PM2.5 & O3 Interaction between water vapor transport & microphysical condensation is the key Daily cycling change of solar radiation supports composite pollution of O3 & PM2.5